西伯利亚雅库特地区岩石圈地幔特征

Characteristics of Sub-continental Lithospheric Mantle Underneath Yakutia Area of Siberia

西伯利亚克拉通是世界上典型的稳定克拉通之一。雅库特地区位于西伯利亚克拉通东北部,有大量的金伯利岩产出,也是世界上金刚石的重要产出地之一。前人研究表明该地区仅在年龄为360 Ma的金伯利岩中有金刚石的产出,而在年龄为160 Ma的金伯利岩中没有金刚石的产出,暗示着雅库特地区岩石圈地幔的性质在160~360 Ma之间可能发生了变化。总结并对比了雅库特地区不同时代喷发的金伯利岩中橄榄岩包体的岩石学、矿物学、地球化学及年代学特征,确定了该地区360 Ma与160Ma的岩石圈地幔在时代与厚度上有很大的不同。这一不同可能与西伯利亚克拉通1.9Ga碰撞拼合事件有关,而与西南部约250 Ma的超级地幔柱事件无关。

Siberian craton is one of the stable craton in the world. Yakutia area, which locates in the northeast of Siberian craton, has a large number of kimberlite outcrops and is also one of the important place of diamond deposit. Previous studies displaced that diamond only occurred in the kimberlite erupted in 360 Ma, but the kimberlites erupted in 160 Ma had no diamond occurrence, indicating the character change of sub-continental lithospheric mantle beneath Yakutia area from 360 Ma to 160 Ma. The petrology, mineralogy, geochemistry and chronology characters of xenoliths from the kimberlite erupted in different episodes of Yakutia area were summarized and compared. The sub-continental lithospheric mantle underneath Yakutia area is varied from 360 Ma to 160 Ma on ages and thickness. This difference may be associated with the Siberian collisional amalgamation event in 1.9 Ga, rather than the super mantle plume around 250 Ma in the southwest.